Ferrite magnetic material

Patent metadata

Field	Value
Publication number	US-9336933-B2
Application number	US-201414456325-A
Country	US
Kind code	B2
Filing date	Aug 11, 2014
Priority date	Jul 8, 2009
Publication date	May 10, 2016
Grant date	May 10, 2016

Abstract

An object of the present invention is to provide a ferrite magnetic material which can provide a permanent magnet retaining high Br and HcJ as well as having high Hk/HcJ. The ferrite magnetic material according to a preferred embodiment is a ferrite magnetic material formed of hard ferrite, wherein a P content in terms of P 2 O 5 is 0.001% by mass or more.

First claim

The invention claimed is:

1. A ferrite sintered magnet composed of a sintered body of a ferrite magnetic material, wherein the ferrite magnetic material comprises hard ferrite and a phosphorus (P) content, characterized in that the P content in terms of P 2 O 5 is 0.005 to 0.1% by mass, wherein the hard ferrite comprises LaCaCo-substituted Sr magnetoplumbite-type ferrite.

2. The ferrite sintered magnet according to claim 1 , wherein the P content in terms of P 2 O 5 is 0.005 to 0.08% by mass.

3. The ferrite sintered magnet according to claim 1 , wherein the sintered body has an arc segment shape having a central angle, wherein the central angle is 60° or more.

4. The ferrite sintered magnet according to claim 1 , wherein the hard ferrite comprises LaCaCo-substituted Sr magnetoplumbite-type ferrite having the formula Sr 1-w-x La w Ca x Fe z Co m O 19 , wherein w=0.127, x=0.116, z=10.36 and m=0.11.

5. The ferrite sintered magnet according to claim 1 , wherein the hard ferrite comprises LaCaCo-substituted Sr magnetoplumbite-type ferrite, wherein the LaCaCo-substituted Sr magnetoplumbite-type ferrite has residual magnetic flux density (Br) of 442.6 mT to 446.4 mT, coercive force (HcJ) of 374.7 kA/m to 386.9 kA/m, and a ratio of external magnetic field strength at 90% of Br (Hj) to HcJ (squareness ratio) of 92.7% to 94.3%.

6. The ferrite sintered magnet according to claim 5 , wherein the ferrite magnetic material has shrinkage in the c-axis direction before and after sintering and shrinkage in the a-axis direction before and after sintering, wherein the ratio of the degree of shrinkage in the c-axis direction before and after sintering to the degree of shrinkage in the a-axis direction before and after sintering (shh/shφ) is 1.73 to 1.82.

Assignees

• Tdk Corp

Inventors

• Nagaoka Junichi
• Mori Takahiro
• Morita Hiroyuki
• Minachi Yoshihiko

Classifications

• C01G51/82

  Compounds containing cobalt, with or without oxygen or hydrogen, and containing two or more other elements · CPC title

• H01F1/10 Primary

  non-metallic substances, e.g. ferrites {, e.g. [(Ba,Sr)O(Fe2O3)6] ferrites with hexagonal structure} · CPC title

• C01P2006/12

  Surface area · CPC title

• C04B2235/3215

  Barium oxides or oxide-forming salts thereof · CPC title

• C04B2235/3262

  Manganese oxides, manganates, rhenium oxides or oxide-forming salts thereof, e.g. MnO · CPC title